The present invention is directed to a shut-off valve for interrupting a flow of a fluid through a pipeline. The present invention is particularly directed to such a valve for interrupting a flow of high temperature air in a gas main associated with a blast furnace, such high temperature air coming from heaters commonly referred to as "cowpers" destined for a blast furnace and eventually to be discharged into the atmosphere.
Modern systems employed to operate blast furnaces and the high temperatures and pressures involved therein cause the size of the mains to be very large and cause the temperature of the air supplied to the blast furnaces to be very high. This causes dangerous working conditions, particularly involved with operation of interception devices, such as shut-off valves, which permit carrying out of the necessary heating cycles and thermal exchange of the cowpers to take place.
Presently known interception devices, of the shut-off valve type and known as "hot air gate valves," are water cooled. Such water cooled shut-off valves however suffer from certain inherent disadvantages. Specifically, the temperature of the cooling water must be kept very low, with the result that there are sudden, cyclical, thermal changes within the structure of the shut-off valve. Additionally, the use of water as a cooling fluid results in massive losses of considerable quantities of heat.